How to change Find_Noms Preference for SCANS

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  • How to change Find_Noms Preference for SCANS

    I'm performing a Find_Noms Scan and while executing it, I got the good ol' error asking me to adjust my tolerance. I mistakenly told it to delete the hits that didnt meet the tolerance: How can I undo this? now whenever I run the feature it will delete a **** ton of points.

    Furthermore, isn't there a better way to check a profile than Find Noms scans? This seems a silly concept to me, since this makes nominals change slightly between executions AND if you have a thin feature you're scanning I don't understand how you can account for ACTUAL deviation in the tolerance without risking piercing the wrong surface.

  • #2
    Press F5 for the setup options. Then click the Warning button. See if that warning is in the list. If it is, click the check in the box to remove it. This happens when you tick the box that says "Don't ask me again" in warning windows.

    I hope that will help.
    PC-DMIS 2016.0 SP8

    Jeff

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    • derekvegeta
      derekvegeta commented
      Editing a comment
      It actually was not one of the listings there for me

  • #3
    Usually the tolerance might be set wrong in your scan for the find nominals .. It should be set to 3 1/2 times the size of your probe plus what ever possible deviation you think you could see on that surface .. Re do your scan and before you hit the generate set the tolerance higher and then run the scan if it stills errors the set tolerance higher . This should help more....
    Michael A Wildschutz Sr
    I Walk on The WildSide
    "To Each is Own"

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    • derekvegeta
      derekvegeta commented
      Editing a comment
      I'm scanning a feature that's .04" Thick: so from what I understand about how Find_noms works, the scan would be able to select the wrong surface. Or am I misunderstanding how Find_noms works?

  • #4
    Originally posted by derekvegeta View Post
    I'm performing a Find_Noms Scan and while executing it, I got the good ol' error asking me to adjust my tolerance. I mistakenly told it to delete the hits that didnt meet the tolerance: How can I undo this? now whenever I run the feature it will delete a **** ton of points.

    Furthermore, isn't there a better way to check a profile than Find Noms scans? This seems a silly concept to me, since this makes nominals change slightly between executions AND if you have a thin feature you're scanning I don't understand how you can account for ACTUAL deviation in the tolerance without risking piercing the wrong surface.
    I think if you go back into the scan dialog and regenerate the scan it will reset it.

    I think if you want to fix your nominals you can select Nominal (instead of find noms), I'm not 100% on this but you may need to execute it offline first to 'fix' the nominals.

    Alternatively you can use find noms, but tick the 'Only selected' tickbox and it will only compare against the surfaces you selected when you created the scan.

    Automettech - Automated Metrology Technology

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    • derekvegeta
      derekvegeta commented
      Editing a comment
      I'm going to repeat back what you said slightly differently to be sure I understand your intent here: doing that will Fix my nominals to whatever the first execution was, the cads nominals since its run offline, and then it shouldn't change in future executions?

  • #5
    Support recommended the use of "Only Selected" for me: anyone use this feature? The help page describes it "When you execute a scan in your measurement routine, and you are searching for the nominal values for the scan's measured points, you can use the Only Selected check box to have PC-DMIS only look for the nominals on the currently selected set of surfaces." which sounds like it's what I'm looking for if I am to stick with Find_Noms

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    • #6
      Originally posted by derekvegeta View Post
      Support recommended the use of "Only Selected" for me: anyone use this feature? The help page describes it "When you execute a scan in your measurement routine, and you are searching for the nominal values for the scan's measured points, you can use the Only Selected check box to have PC-DMIS only look for the nominals on the currently selected set of surfaces." which sounds like it's what I'm looking for if I am to stick with Find_Noms
      I always use that. You 100% have to if you are working thin parts, otherwise, WHICH side of the part will it select? If the part is 1mm thick and off by more than 1mm, you'll get BAD data.
      sigpic
      Originally posted by AndersI
      I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

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      • derekvegeta
        derekvegeta commented
        Editing a comment
        So I've been using that (I have frequently .02" thick parts I need to check profiles on), and the nominals are not making sense... Its a rotary scan normal to my Z+ Workplane, so why is it that my nominals for hits in the Z has a tilt using Find_noms? I see it go from the Correct Z on the first point, and .0001" at a time it descends upto .011" (which on my .02" thick feature is a lot)

        And why is it that my find_noms tolerance needs to be adjusted within the scans? (its currently at .125" using a 2mm probe BUT it wouldnt accept my tolerance no matter how high I attempted to make it... So i hit No, dont find new tolerance, and then told it No, dont remove hits (because I wanted to see where it thought the hit was so far off) but no T values exceed .017 and the part is registering in tolerance

      • Matthew D. Hoedeman
        Matthew D. Hoedeman commented
        Editing a comment
        check your cut plane, if you want them all at the same Z, then the cut plane MUST be 0,0,1, as well as the 1, D, 2 points have to have the same Z value. For the other, check the vectors of the surfaces, if some go one way and some the other, then it won't find noms.

      • derekvegeta
        derekvegeta commented
        Editing a comment
        Rotary Scans (2019 R2) do not have cut planes. The start, end, and direction vectors all have the same Z, and when I create the path it has the same Z but after executing it, it changes (presumably find_noms doing its thing)

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